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Full text of "Practical Organic Chemistry"

ETIIVL ACF.TOACICTATE

between 115 and 120.    Weigh  the  distillate.    This process
furnishes an example of fiytfwlysis or saponijication,
CH;t.COOCaHr, + H,O - CH.,.COOH + C2HfiOH.
See Appendix, p. 247.
PREPARATION 16.
Ethyl Acetoacetate (Acetoacetic Ester),
c: H 3. c: o. c H B. c o. o c, 11 f).
Geuther, JaJtrcsb., 1863, p. 323; Frankland, Duppa, . Phil
Tram., 1865, 156, 37 ; Wislicenus, Annalen, 1877, 186, 161.
200 grms. ethyl acetate.
20          sodium.
The ethyl acetate, carefully dehydrated as described in the
previous preparation, is introduced into a round flask (4 litre)
connected with a long upright condenser. 20 grams well pressed
sodium, cut into thin slices, are quickly added, and the flask
cooled in water. After a short time a brisk reaction sets in, and
ultimately the liquid boils. When the first action is over, and
no further evolution of heat occurs, the mixture is heated on the
watcr-b.'ith, without detaching the condenser, until the sodium is
completely dissolved. A 50 per cent, acetic acid solution is at
once added and well shaken, until the liquid is acid, (about
TOO c.c), and then an equal volume of concentrated brine. The
liquid divides into two layers ; the upper one, consisting of
acetoacetic ester and unchanged ethyl acetate, is carefully
separated. Jt is distilled over wire-gauxe until the thermometer
marks 100, and all the ethyl acetate has been removed. The
distillate is now collected in five fractions (roo 130'', 130135?
165175, 175-185, 185200"). The fraction distilling at
* 175185 is nearly pure acetoacetic ester. Yield 3040 grams.
A further quantity may be obtained by redistilling the other
fractions ; but it is undesirable to repeat the process frequently,,
as acetoacetic ester gradually decomposes at the boiling point.
It is for this reason that Gattennann recommends the fractional
distillation to be carried out in vttcito.
The brown residue remaining in the distilling flask solidifies,
on cooling, to a crystalline mass consisting chiefly of dehy-
G   2